David dorward



(No Model.)

TUBULAR METALLIC POLE- No. 484,144. Patented 004. 11, 1892.

,Z? G 014%.. J

UNITED STATES PATENT OFFICE."

DAVID DORWARD, OF SAN FRANCISCO, CALIFORNIA, ASSIGNOR TO THE RISDON IRONAND LOCOMOTIVE WORKS, OF SAME PLACE.

TU BU LAR M ETALLIC POLE.

SPECIFICATION forming part of Letters Patent No. 484,144, dated October11,1892. Application filed April 25, 1892. Serial No. 430,488. (Nomodel.)

To all whom it may concern.-

Be it known that I, DAVID DORWARD, a citizen of the United States,residing at San Francisco, in the county of San Francisco and State ofCalifornia, have invented certain new and useful Improvements in TubularMetallic Poles; and I do hereby declare that the following is a full,clear, and exact description thereof.

My invention relates to the construction of metallic poles intendedespecially to support elevated electrical conductors, such as telegraph,telephone, and electric-light wires.

The invention relates more particularly to improvements upon aconstruction described and shown in Letters Patent granted to me March1, 1892, No. 47 0,153. In that patent I described and showed a polecomposed of metallic tubular sections supported within one another so asto leave an annular space between them, which space was filled with acomposition which rigidly united the sections when the pole was set up.At the bottom of the inner section the annular space was closed by aring secured, preferably, to the base of the inner section, and thusenabling the composition to be inserted into the space between thetubes. The object of the invention thus describedwas, as set forthin thepatent named,

to provide a sectional pole which would be exceedingly cheap tomanufacture and which would have the additional advantage of bein gcapable of transportation in sections, while when set up it would formpractically a continuous pole of as great strength and durability as apole composed of a single section.

My present invention differs from that just described in certain detailsof construction intended to still further reduce the cost of manufacturewithout in any way impairing the strength or effectiveness of thedevice.

My invention is illustrated in the accompanying drawings, in which-Figure 1 is a vertical section of a part of my pole, taken at one of thejoints. Fig. 2 is a cross-section on the line as as.

My improved pole, like that described in my patent referred to, iscomposed of any de sired number of metallic tubular sections.

Referring to Fig. 1, which illustrates the union of any two of thesetubular parts, A

represents one section of tubing, and B an adjoining section above. Thetwo tubes may be supposed to be, respectively, six inches and fiveinches in diameter, so that an annular space is left between them. Itwill be understood, however, that neither the diameters of the tubes northe thickness of the metal of which they are composed are essentialpoints, as they may be varied to suit different conditions. The tube Bpreferably rests upon a transverse rivet or pin 1, driven through thelarger tube and forming a stop. Any other form of stop sufficient tosupport the inner tube may be used instead, or the pin may, ifpreferred, be placed higher up and driven through both tubes. As statedbefore, in my former patent the annular space was closed at the bottomby a ring secured to one of the tubes. In the present case this ring isdispensed with and the space is closed by spreading the lower edge ofthe inner tube until it is of the inner diameter of the tube surroundingit, and will therefore come into contact with the latter when inserted.The space between the two tubes is filled with a composition, preferablythat mentioned in my patent referred to, which forms what is known as arust-joint, and is usually composed of iron filings, sal-ammoniac, andwater. Other substances or compositions may, however, be used instead,such as melted sulphur or lead, and, indeed, a short sleeve or tube maybe inserted into the annular space, which will be the equivalent of thehardened filling. In the latter case it will not be necessary to use thekeys or Wedges 2, described in'my former patent, since such a sleevewill keep the sections concentric; but when the composition filling isemployed I prefer to use such keys or wedges as shown in the drawings.

By dispensing with the ring shownin my The combination of an outertube,an inner nature, in presence of two witnesses, this 9th tube of smallerdiameter inserted therein and day of April, 1892. having its lower edgespread so as to close the annular space between the two tubes, and aDAVID DORWARD' 5 filling in said annular space, substantially asWitnesses:

L. W. SEELY, W. E. CARROLL.

set forth.

In testimony whereof I have affixed my sig-

